A variety of physical conditions involve two tissue surfaces that, for treatment of the condition, need to be distracted from one another and then supported away from one another. Such distraction may be to gain exposure to select tissue structures, to apply a therapeutic pressure to select tissues, to return tissue structures to their anatomic position and form, or in some cases to deliver a drug or growth factor to alter, influence or deter further growth of select tissues. Depending on the condition being treated, the tissue surfaces may be opposed or contiguous and may be bone, skin, soft tissue, or a combination thereof. An optimal treatment method includes distracting and supporting the tissue surfaces simultaneously.
A minimally invasive distraction and support device would have significant application in orthopaedic surgical procedures, including acute and elective procedures to treat bone fractures and degenerative changes of the skeletal system and including vertebral compression fractures, interbody fusion, vertebral disc augmentation or replacement, and other compression fractures including, but not limited to tibial plateau compression fractures, calcaneous compression fractures, distal tibia fractures, distal radius (wrist) fractures, crushed or fractured orbit and orthopaedic oncology. Further, a minimally invasive distraction and support device would have application in non-orthopaedic surgical procedures in plastic surgery (for example facial reconstruction), gastrointestinal surgery and urological surgery (for example the treatment of incontinence).
One technique used to treat vertebral compression fractures is injection of bone filler into the fractured vertebral body. This procedure is commonly referred to as percutaneous vertebroplasty. Vertebroplasty involves injecting bone filler (for example, bone cement) into the collapsed vertebra to stabilize and strengthen the crushed bone. In this procedure, lower viscosities and higher pressures tend to disperse the bone filler throughout the vertebral body. However, such conditions dramatically increase the risk of bone filler extravasation from the vertebral body.
Kyphoplasty is a modified vertebral fracture treatment that uses one or two balloons, similar to angioplasty balloons, to attempt to reduce the fracture and restore vertebral height prior to injecting the bone filler. Two balloons are typically introduced into the vertebra via bilateral transpedicular cannulae. The balloons are inflated to reduce the fracture. After the balloon(s) is deflated and removed, leaving a relatively empty cavity, bone cement is injected into the vertebra. In theory, inflation of the balloons restores vertebral height. However, it is difficult to consistently attain meaningful height restoration. It appears the inconsistent results are due, in part, to the manner in which the balloon expands in a compressible media and the structural orientation of the trabecular bone within the vertebra.
A tibial plateau fracture is a crushing injury to one or both of the tibial condyles resulting in a depression in the articular surface of the condyle. In conjunction with the compression fracture, there may be a splitting fracture of the tibial plateau. Appropriate treatment for compression fractures depends on the severity of the fracture. Minimally displaced compression fractures may be stabilized in a cast or brace without surgical intervention. More severely displaced compression with or without displacement fractures are treated via open reduction and internal fixation.
Typically, the underside of the compression fracture is accessed either through a window cut (a relatively small resection) into the side of the tibia or by opening or displacing a splitting fracture. A bone elevator is then used to reduce the fracture and align the articular surface of the tibial condyle. A fluoroscope or arthroscope may be used to visualize and confirm the reduction. Bone filler is placed into the cavity under the reduced compression fracture to maintain the reduction. If a window was cut into the side of the tibia, the window is packed with graft material and may be secured with a bone plate. If a splitting fracture was opened to gain access, then the fracture is reduced and may be stabilized with bone screws, bone plate and screws, or a buttress plate and screws. Both of these methods are very invasive and require extensive rehabilitation.
Spinal fusion is most frequently indicated to treat chronic back pain associated with instability or degenerative disc disease that has not responded to less invasive treatments. Fusion is also prescribed to treat trauma and congenital deformities. Spinal fusion involves removal of the spinal disc and fusing or joining the two adjacent vertebrae. The primary objective for patients suffering from instability is to diminish the patient's pain by reducing spinal motion.
Spinal fusions are generally categorized into two large groups: instrumented and non-instrumented. In non-instrumented procedures, the physician removes tissue from the unstable disc space and fills it with some form of bone graft that facilitates the fusion of the two adjacent vertebral bodies. Instrumented procedures are similar to non-instrumented procedures, except that implants (generally metallic) are also applied to further stabilize the vertebrae and improve the likelihood of fusion.
In all interbody surgical approaches, a relatively large opening is made in the annulus. The nuclear material is removed and the end plates are decorticated to facilitate bony fusion. Overall, the use of interbody devices has resulted in mixed clinical outcomes. Placement of a fixed height device presents challenges in proper tensioning of the annulus. For these and other reasons, there is concern over long-term stability of interbody devices and fusion mass.
A need remains for a system and method for distracting or elevating adjacent tissues that is minimally invasive and more easily implemented. Moreover, the system and method should provide a simplified capability for quantifying and controlling the amount of distraction. The system and method should also permit additional augmentation of the distraction site.